Does gamma equal density in Kg/m^3?

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Discussion Overview

The discussion revolves around the relationship between weight density (gamma) and mass density, particularly in the context of using the equation for force due to fluid pressure. Participants are exploring the units involved and whether a conversion is necessary when using density in calculations.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that gamma (γ) is defined as the product of mass density (ρ) and the acceleration due to gravity (g), expressed as γ = ρ ⋅ g.
  • There is a question about whether the expression pgh is in N/m^3 or kg/m^3, indicating confusion about the units involved.
  • One participant suggests that if density is provided in kg/m^3, it may be necessary to multiply by 9.81 to convert it to the appropriate units for the equation.
  • Another participant challenges this suggestion, implying that the units of ρgh should be clarified and that a careful review of the previous post is needed.

Areas of Agreement / Disagreement

Participants express differing views on the unit conversions and the relationship between mass density and weight density. The discussion remains unresolved regarding the necessity of conversion and the interpretation of the units.

Contextual Notes

There is a lack of consensus on the interpretation of units and the application of the equation, with some assumptions about the definitions of weight density and mass density remaining unexamined.

Parsifal1
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I want to use the equation:

Fr='gamma'*distance from centroid*Area

but the example is showing density in N/m^3

while I only have the density in kg/m^3

Does this mean I have to multiply it by 9.81 to get the right answer?

Thanks.
 
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Parsifal1 said:
I want to use the equation:

Fr='gamma'*distance from centroid*Area

but the example is showing density in N/m^3

while I only have the density in kg/m^3

Does this mean I have to multiply it by 9.81 to get the right answer?

Thanks.
γ is known as the 'weight density' of a substance. γ = ρ ⋅ g, where ρ is the mass density and g is the acceleration due to gravity.
 
SteamKing said:
γ is known as the 'weight density' of a substance. γ = ρ ⋅ g, where ρ is the mass density and g is the acceleration due to gravity.
So, pgh is expressed in N/m^3 as opposed to Kg/m^3?
 
Parsifal1 said:
So, pgh is expressed in N/m^3 as opposed to Kg/m^3?
No. Re-read Post #2 again carefully and then work out the units of ρgh versus just ρg.
 

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